The hospital as a place where people go to get better is comparatively recent, and the transformation involved several distinct changes.
What they were before
Institutions providing shelter and care to the poor and dying, generally run by religious orders or by charity.
Which means people with means were treated at home, and the hospital was where you went if you had no alternative.
Mortality within them was high enough that avoiding them was rational.
Anaesthesia
Surgery before it was limited to procedures achievable in the time a person could endure.
Which meant speed was the surgeon's primary skill, and internal procedures were essentially impossible.
General anaesthesia removed the time constraint entirely, and it expanded the surgical possibility set enormously.
Antisepsis
Post-surgical infection killed a large proportion of patients who survived the operation.
Which was addressed through the recognition that infection was caused by transmissible agents rather than arising spontaneously.
Handwashing, instrument sterilisation and antiseptic technique reduced mortality dramatically, and their adoption was slower and more contested than retrospective accounts suggest.
Nursing
Professionalisation of nursing changed institutional practice substantially.
Which included training, hierarchy, record-keeping and attention to ventilation, sanitation and nutrition.
Statistical work demonstrating the effect of conditions on mortality was influential in driving reform.
Imaging
The ability to see inside a living body without opening it.
Which transformed diagnosis, and it required equipment that concentrated care in institutions.
Subsequent imaging technologies extended this and reinforced the concentration, since the equipment is expensive and requires trained operators.
The concentration effect
As treatment required equipment and specialists, care moved from the home into institutions.
Which changed who hospitals served — from the poor to everyone — and changed how healthcare was financed.
Insurance systems and public provision both developed substantially in response to the cost of institutional care.
Antibiotics
Made previously fatal infections treatable and made major surgery survivable.
Which transformed outcomes and produced the resistance problem that now constrains them.
Hospitals are where resistant organisms concentrate, which is a direct consequence of concentrated antibiotic use.
The reversal
Care is now moving back out of hospitals where possible.
Day surgery, community care, remote monitoring and hospital-at-home schemes all reflect this.
Which is driven by cost, by infection risk and by evidence that outcomes for some conditions are comparable or better outside institutional settings.
Specialisation
Medicine divided into specialties as knowledge accumulated beyond what any individual could hold.
Which improved depth and produced coordination problems, since patients with multiple conditions see multiple specialists.
General practice developed as the coordinating function, and its relationship with specialist care differs enormously between health systems.
Evidence-based medicine
The movement toward basing practice on systematic evidence rather than on authority and experience.
Which developed from the mid twentieth century and produced randomised trials as the standard for assessing treatment.
Systematic reviews aggregating evidence, and the organisations producing them, followed.
Adoption has been uneven, and the gap between evidence and practice is a documented and persistent problem.
Hospital-acquired infection
Concentrating vulnerable patients produces transmission.
Which is addressed through hygiene, isolation, antibiotic stewardship and surveillance.
Rates are published in several systems, and improvement has been substantial where measurement drove attention.
Funding models
Tax-funded, insurance-based and mixed systems produce different incentives.
Which affects what is provided, to whom and at what cost, and international comparison of outcomes against spending is published regularly.
Administrative costs differ substantially between models, which is one of the clearer findings from comparison.
The teaching hospital
Institutions combining treatment with training and research.
Which concentrated expertise and produced better outcomes for complex conditions, and it created a hierarchy between institutions.
Volume-outcome relationships, where institutions performing more of a procedure achieve better results, have been documented for several procedures.
Patient safety
Recognition that healthcare itself causes substantial harm developed comparatively recently.
Which followed studies quantifying adverse events in hospitals and finding rates that were far higher than assumed.
Systems approaches borrowed from aviation and other high-risk industries followed, focusing on system design rather than individual blame.
Waiting and capacity
Queueing dynamics mean that systems running near full capacity produce disproportionately long waits.
Which is why occupancy targets below full capacity exist, and why running hospitals at very high occupancy produces the outcomes it does.
Discharge capacity in community and social care constrains hospital flow directly, which is why the two cannot be planned separately.
The workforce
Healthcare is labour-intensive and workforce constraints determine capacity more than buildings or equipment.
Which means training pipelines measured in years determine what is possible, and decisions made a decade ago constrain current capacity.
International recruitment fills gaps and raises questions about effects on source countries.
Emergency care
Departments have become the default point of access where other services are unavailable or unavailable quickly.
Which produces crowding driven by factors outside the department, particularly the availability of alternatives and of beds to admit into.
Crowding is associated with worse outcomes, which is documented and is a system problem rather than a departmental one.